Transformer



J. L. BONANNO TRANSFORMER June 9,. 1953 Z'Sheecs -Sheet 1 Filed July 26, "1949 INVENTOR Jsspa A. Equmwva BY '5 12! W ATTORNEY Patented June 9, 1953 2 TRANSFORMER Joseph L. Bonanno, Madison, N. J assignor to The Lionel Corporation, New York, N. Y., a corporation of New York Application July 26, 1949, Serial No. 106,860

3 Claims. (Cl. 336-90) 1 The present invention relates to transformers and is more particularly directed toward transformers suitable for use with toy railroads.

The present invention is particularly well suited for transformers for use on the usual 110 volt house circuit and operating comparatively small loads with comparatively low secondary voltages, such as 9 to 13 volts.

Transformers for this purpose should be designed for low manufacturing cost, and the present invention is directed toward low cost, low wattage, variable voltage output transformers for toy trains and other similar low voltage alternating current operating apparatus.

The present invention contemplates the use of a pre-assembled transformer unit having laminated field and primary and secondary windings with part of the latter winding exposed to provide for variable voltage take-off, a plastic cover or box adapted to receive the field-winding unit and hold it in place, and a base adapted for convenient assembly with the cover, the base holding the transformer unit in place without the use of attachments, screws and other devices.

Other and further objects will appear as the description proceeds.

The accompanying drawings show, for purposes of illustrating the present invention, one embodiment in which the invention may take form, it being understood that the drawings are illustrative of the invention rather than limiting the same.

In the accompanying drawings:

Figure 1 is an exploded perspective view showing the cover With field-winding unit and the base;

Figure 2 is an inverted plan view showing the cover and wiring parts carried by it in full lines, and the field and coil in dotted lines;

Figure 3 is a transverse sectional view on the line 33 of Figure 2, showing the complete transformer assembled;

Figure 4 is a side elevational view taken in the direction of the arrow 4 of Figure 3, with parts broken away, showing interior construction; and

Figure 5 is a wiring diagram.

The transformer field I0 is of usual rectangular form and carries the primary Winding I I and secondary winding 12 as usual. A portion of the secondary winding is wound about an insulating terminal plate 13 and insulation is scraped off to provide a flat surface, as indicated at [4, from which voltages of varying amount may be obtained. The primary winding for the 2 transformer is. connected to a two-conductor lamp cord, as indicated at I4, and one end of the secondary winding is connected to a wire The cover 28 is a molding preferably made of phenyl-formaldehyde and is in the form of an inverted five-sided box with a top wall 2|, ends 22, 22 and sides 23, 23. The top of the box carries two binding posts 25 and 26. The binding post 25 is connected to a solder-ing lug 21 and the binding post 26 is connected with an L- shaped strap 28. The strap 28 is in contact with hub 29 of a contact arm 29 carried by an'operating finger 30 so that the arm 29 may be swung back and forth. The molding 20 has internal corner ribs 30 which engage the corners of the field structure 10 and hold the structure against movement lengthwise of the box. Adjacent the corner elements 30 are ribs 3| having downwardly facing shoulders 32. These ribs below the shoulders 32 engage the sides of the transformer field, and the shoulders 32 form stops limiting the upward movement of the transformer field into the housing. This definitely locates the field and coil as well as the bared portion [4 of the secondary so that the contact arm 29 can be swept across the secondary to pick off variable voltages. The secondary lead I5 is connected to the binding post 25.

The base shown generally at is made of two pieces of sheet metal 4| and 42; the lower one has upwardly extending bumps 43 welded to downwardly extending bumps 44 carried by the upper sheet metal part. The sheet metal part 42 has side flanges indicated at 45 and 46. These side flanges have just the proper width to fit portions 47, 48 of the inside walls of the casing. The sheet metal member 42 is also provided with two upwardly bent members 49 and 50, here shown as bifurcated, each having side elements 5|, 5| and each side element being provided with teeth 52 which face downwardly.

The inner walls of the casing have ribs 53, 53 preferably of key-shaped cross-section as indicated in Figure 2 of the drawings. The width of these ribs in such that the tooth members engage them very tightly when the plastic cover and the metal base are pressed toward one another. The teeth may wear away a small amount of plastic material and tend to spring slightly during this operation, so that the metal tightly grips the plastic so as to prevent accidental removal or separation of the parts. The current supply cord [4 is knotted as indicated at 54 and passes through an opening 55 in the wall of the cover, as indicated.

The assembly of the parts is very easy, rapid, and inexpensive, and the electrical testing may be completed, if desired, before the cover and base are pressed together.

Since it is obvious that the invention may be embodied in other forms and constructions within the scope of the claims, I wish it to be understood that the particular form shown is but one of these forms, and various modifications and changes being possible, I do not otherwise limit myself in any way with respect thereto.

What is claimed is:

1. A variable voltage step-down transformer having a preassembled voltage reducing unit with rectangular magnetizable field structure, primary winding, and secondary winding, part of the latter winding having an upper exposed contact face, a housing unit in the form of a down- I wardly opening molded insulating body closed at the top and having guide members to slidably receive the field structure and position it in the housing; and stops to space the contact face of the secondary below the top of the housing, a pivoted contact arm secured to the under face of the insulating body and bearing on the face of the secondary winding, an arm operating finger secured to the contact arm and disposed above the top of the insulating body, two binding posts carried by the top of the body, a fixed conducting strap extending from one binding post to the arm pivot; a wire connecting the other binding post with the secondary winding; and a metal base secured to the housing, the base engaging the bottom of the core to hold it against the stops.

2. In a step-down transformer, in combination, a transformer housing of inverted cupshaped configuration carrying binding posts, a sweep arm and connecting strap from the sweep arm. to one binding post to form a preassembled 4 unit, the housing having vertical alignment guides and downwardly facing stop lugs, a transformer field structure of a configuration to fit the guides and be held against the stop lugs, a primary winding and a secondary winding having a contact face cooperable with the sweep arm, and a lead connected to the other binding post, and a bottom closure member having upwardly extending members disposed alongside the transformer field, said members carrying downwardly facing teeth, the side walls of the housing having ribs engageable by said teeth to resist removal of the closure member once it has been positioned.

3. As an article of manufacture for use with a transformer having a rectangular field structure oi'predetermined dimensions and carrying an exposed secondary coil on its upper face, a downwardly opening housing having four pairs of internally disposed guide members engageable with the field structure at the corners and four downwardly facing stops, one adjacent each corner to engage with the upper face of the inserted field and space the coil below the top of the housing, a pivoted conducting arm carried by the top of the housing and adapted to bear on the exposed coil, a binding post carried by the top, and a strap permanently connecting the binding post and the pivot.

J O'SEPH L. BONANNO.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Re.1'9,957 Smith 1 May 5, 1936 1,213,792 Bonner Jan. 23, 1917 1,576,527 McBride Mar. 16, 1926 1,645,165 Shackelton .c Oct. 11, 1927 1,918,987 Seabold July 18, 1933 2,114,189 Kronmiller Apr. 12, 1938 2,318,608 Hempel May 11, 1943 2,446,1 1 Parsons 1.. July 27, 1948 

